Objective: To review the clinical characteristics of struma ovarii.Methods: Fifty-three cases of struma ovarii treated in this hospital from January 1988 to January 2008 were analyzed retrospectively, and related literatures were reviewed.Results: Struma ovarii accounted for 1.5% of ovarian teratomas diagnosed at the studied period. The mean age of onset was 39.5 years. All cases were unilateral, occurring equally in either side, with a normal contralateral ovary. Elevated serum levels of CA125 (50-2265.7 U/ml) were observed in all 5 patients with ascites. There were no characteristic imaging findings and the confirmed diagnosis was dependent on histology. The management for all patients was surgery. No reoccurrence was found within mean follow-up of 58 months after operation. Conclusion: Struma ovarii is rare and occurs more often in late reproductive age, with a good prognosis. It is difficult to be diagnosed before surgery, and should be distinguished from malignant ovarian tumor. Laparoscopy is the best choice of treatment.